This is a Program Project designed to investigate processes that control remodeling of the extracellular matrix of skeletal and other connective tissues and the role of selected inflammatory mediators (cytokines) and hormones that regulate these processes. The ultimate aims are to identify controls of matrix deposition and resorption that would explain pathological events in inflammatory joint diseases such as rheumatoid arthritis and bone diseases such as Paget's disease. The approaches to achieve these aims utilize techniques of biochemistry, cell and molecular biology. Collagens are the major macromolecules of interest. In this proposal, an emphasis is on collagenase, member of the matrix metalloproteinase family. The mechanisms of proposal, an emphasis is on collagenase, a member of the matrix metalloproteinase genes, particularly that exerted by inflammatory mediators such as interleukin-1 (IL-1), and the precise role of collagenase in remodeling of the matrix will be explored. The focus in on IL-1, particularly the molecular mechanisms critical to interactions of IL-1 with its receptor and the pathways by which IL-1 induces signals. These processes will be investigated further with respect to effects of IL-1 on collagen synthesis by fibroblasts and chondrocytes in order to understand controls of repair of the extracellular matrix in inflammation. Studies of the mechanisms of osteoclast-mediated bone resorption is another important aspect of this proposal. Osteoclasts have receptors for the hormone calcitonin receptors has been accomplished in this laboratory making it possible to use molecular approaches to study signal transduction and the role of the receptors and ligands in development. The investigators in goal, ideas, techniques and materials. In Project 1, "Degradation of Collagen" the goals are to understand the mechanisms of collagenase action using site- directed mutagenesis of the collagen substrate, and expressing the mutations in cultured cells and transgenic mice. Mutations will also be made in the collagenase gene in order to interrupt its function in vivo. In Project 2, "IL-1-Mediated Inflammation", its receptors in inducing intracellular signals and transcription of the collagenase gene. In Project 3, "Collagen Synthesis in Inflammation, the goals are to understand how inflammatory mediators such as IL-1 alter the pattern of synthesis of collagens in different mesenchymal cells through regulation of gene transcription. In Project 4. "Function of Calcitonin Receptors", the goals are to define the molecular basis of the effects of calcitonin by exploring the unique properties of the calcitonin receptors. In Project 5, "Calcitonin Receptor in Development", the diverse roles of the receptor will be examined in mice and zebrafish. The structure of the gene will be determined and transgenic animals produced in which the function of the gene is disrupted.